What is causes a male to vomt bile EVERY morning?

Every morning my friend vomits bile. I've already read about how to avoid neausea in the mornings etc but i still don't uderstand why he keeps vomitting bile. This cant be healthy for him to keep doing that. The doctors just say that its due to congestion and that makes you neauseated, which i agree to a certain point, but even when there is no congestion he still wakes up and vomits bile. He does not smoke, drink, or do drugs. Help please!